Electric forging apparatus



March 9, 1943.

W. F. HEINEMAN ELECTRIC FORGING APPARATUS Filed May 1, 1941 Warren E Heineman INVENTOR.

ATTORNEY.

Patented Mar. 9, 1943 ELECTRIC FORGING APPARATUS Warren F. Heineman,Milwaukee, Wis., assignor to A. 0. Smith Corporation, Milwaukee, Wis., acorporation of New York Application May 1, 1941, Serial No. 391,234

10 Claims.

This invention relates to.electric forging apparatus and constitutes animprovement upon apparatus heretofore proposed for the nosing down andthickening of tubes in the manufacture of bomb shells and various otherproducts.

The principal object of the invention is to provide for more uniformcontact between the electrodes which constitute the forming dies and thepiece being formed.

Another object of the invention is to provide a more efllcient apparatusfor the use of three phase current for heating.

A further object is to provide more uniformheating conditions andprevent undue heating of the shell at the end of the nose.

One embodiment of the invention is illustrated in the accompanyingdrawing in which:

Figure 1 is a schematic view of the apparatus showing a longitudinalsection through th dies and showing the shell being formed;

Fig. 2 is an enlarged end view of the dies partly in section, and aschematic showing of the electric circuit employed; and

Fig. 3 is a longitudinal section through the completed nose of a bombshell formed by the dies.

The apparatus comprises in general, a set of forging dies l suitablysupported on a standard 2, and'a chuck 3 supported on a standard 4. Thetwo standards 2 and l are mounted for relative movement toward and awayfrom each other on a bed 5, and the dies I and. chuck 3 are disposed inalignment and supported for rotation relative to each other.

Preferably, the standard 2 is moved along suitable guideways on the bedby a ram 6. And also preferably the chuck 3 which has suitable clamps Ifor holding the tube 8 being formed, is rotated by a motor 9 mounted onstandard 4.

The dies i comprise three separate electrodes l0, II and I2, eachconnected at adjacent ends to transformer leads l3, I4 and i5,respectively, and which supply a three phase current to the electrodes.

The electrodes are complementary, and except for a space between theadjacent edges of the same they provide a cup-shaped die-having therequisite shape for forming the nose on the end of tube 8 as the latteris advanced into the die.

The electrodes i0, I i and I! are insulated from one another and fromthe standard 2 in which they are held.

as the tube 8 advances into the dies i, its end engages the innersurface of the electrodes II,

II and I2 andheating current following the 55 path of the dotted linesin Fig. 2 passes through the metal of the tube bridging the gaps betweenthe respective electrodes. Rotation of the tube 8 effects heating of acircumferential portion of the tube end, and as the tube softens, thepressure of the tube against the dies effects an inward forming of theend of the tube.

Progressive movement of tube 8 into the dies i effects a gradual andprogressive heating and forming of the end of the tube until the nose I6is completed thereon, the walls of the tube being forced inwardly andthickened as shown in Fig. l.

The internal shape of the dies will depend upon the desired finishedshape of the work piece and may vary from conical to any curvedsymmetrical shape desired. The dies may be shaped for purely upsettingoperations or for forming either internal or external flanges or tubes.

The invention has very considerable advantage over the two half dieconstruction heretofore proposed, and in which the dies were shapedsomewhat elliptical to provide the required electrical contact forheating. In the present invention, by providing three electrodes auniform contact with the pipe is provided at the adjacent edges of theelectrodes.

The power saving by the efficient use of three phase current is anotheradvantage of the invention. Furthermore only that part of the tube thatis to be formed is heated and there is substantially no waste of heat.

It has been found that there is a tendency for the current to flowtoward the end of the nose and to heat the metal at the end of the pipe8 more than is necessary. When the metal gets too soft, there is lesscontrol of the forming of the same.

This difliculty is substantially overcome by attaching the leads I3, I4and ii to their respective electrodes i0, ii and I! at or near theregion of greatest internal diameter or open end of the dies I. Thisprovides a longer path for current flowing toward the tip of the nosethan for that flowing through the pipe 8 at regions of larger diameter.As a result the major heating zone in the dies is near the region wherethe pipe first engages the dies as a forming operation is started.

While the invention has been illustrated as applied to apparatus for theforging of the ends on tubes in the manufacture of bomb shells, it maybe applied to apparatus for other purposes.

The invention may have various embodiments within the scope of theaccompanying claims.

I claim: I

1. In an electric forging apparatus at least three complementarysymmetrically shaped electrodes constituting forming dies presentingradially opposed circumferential forming surfaces for engagement by arelatively rotating work piece, said electrodes being spaced apart toapply a heating current passing from one electrode to another through apart of the work piece being formed.

2. In an electric forging apparatus, three complementary symmetricallyshaped electrodes constituting forming dies presenting radially opposedcircumferential forming surfaces for engagement by a relatively rotatingwork piece, said electrodes being spaced apart to apply a heatingcurrent passing from one electrode to another through a part of the workpiece being formed, and means connecting said electrodes respectively tothe separate leads of a three phase current source.

3. In an electric forging apparatus, at least three complementarysymmetrically shaped electrodes constituting forming dies presentingradially opposed circumferential forming surfaces for engagement by arelatively rotating work piece, said electrodes being spaced apartcircumferentially to apply a heating current to that part of the workpiece being formed passing from one electrode to another in a generallycircumferential direction.

4. In an electric forging apparatus, three complementary symmetricallyshaped electrodes constituting forming dies presenting radially opposedcircumferential forming surfaces for engagement by a relatively rotatingwork piece, said electrodes being spaced apart circumferentially toapply a heating current to that part of the work piece being formedpassing from one electrode to another in a generally circumferentialdirection, and means connecting said electrodes respectively to theseparate leads of a three phase current source.

5. In an electric forging apparatus, three cornplementary symmetricallyshaped electrodes constituting forming dies presenting radially opposedcircumferential forming surfaces for engagement by a relatively rotatingwork piece, said electrodes being spaced apart circumferentially toapply a heating current to that part of the work piece being formedpassing from one electrode to another in a generally circumferentialdirection, and means connecting said electrodes respectively to theseparate leads of a three phase current source, said leads beingconnected to the respective electrodes at the outer circumference nearthe forward end where contact is first made with the work piece.

6. In an electric forging apparatus, a plurality of electrodesconstituting radially opposed forming dies having complementarysymmetrical circumferential forming surfaces for engagement by arelatively rotating work piece, said electrodes being spaced apartcircumferentially and connected to a source of electric energy to applya heating current to the part of the Work piece being formed, theelectrical lead connections to the respective electrodes being at theouter circumference near the forward end of each electrode where contactis first made with the work piece.

7. In an apparatus for nosingdown and thickening the end of a tube inmanufacturing bomb shells and the like, a plurality of electrodesconstituting forming dies disposed circumferentially and shaped toprovide a common die recess having the shape of the nose to be formed onthe tube, and leads from a source of electricity connected to saidelectrodes at the outer forward ends thereof, said electrodes beingspaced apart circumferentlally to provide for passing current throughthe tube at the gaps between the electrodes.

8. In an apparatus for nosing down and thickening the end of a tube inmanufacturing bomb shells and the like, a plurality of electrodesconstituting forming dies disposed to provide a common die recess havingthe shape of the nose to be formed on the 'tube, said electrodes beingspaced apart to provide gaps therebetween, and means connecting theelectrodes to a source of alternating electric energy having a pluralityof phases to provide a heating current of different phase passingthrough the tube across the gap between each respective pair ofelectrodes.

9. In an electric forging apparatus of the class described, a pluralityof spaced complementary symmetrically shaped electrodes constitutingforming dies presenting radially opposed circumferential formingsurfaces for engagement by a relatively rotating work piece, and meansconnecting said electrodes respectively to the separate leads of asource of multi-phase alternating current to provide for a heatingcurrent of different phase relation passing through the work pieceacross the gap between each pair of electrodes.

10. In an apparatus of the class described a plurality of opposedelectrodes disposed to make recurrent contact with portions of anarticle being heated for a substantial distance longitudinally of theelectrodes, and electrical connections supplying current to saidelectrodes and providing therewith current paths of different electricalimpedance to effect a predetermined differential distribution of theheating current to the article in different longitudinal regions ofcontact of said electrodes.

WARREN F. HEINEMAN.

